The presence of platelet-activating factor (PAF) in normal human mixed saliva

Abstract

This report describes PAF activity in normal human mixed saliva from each of 24 randomly selected donors. The human salivary PAF (HS-PAF) was similar to rabbit basophil PAF (acetyl glyceryl ether phosphorylcholine or AGEPC) with respect to the following characteristics: 1. HS-PAF co-chromatographed with the standard rabbit basophil AGEPC and with synthetic AGEPC. 2. HS-PAF and AGEPC were unaffected by hirudin, indomethacin, and creatine phosphate/creatine phosphokinase, the respective inhibitors of platelet activation induced by thrombin, arachidonic acid, and ADP. 3. HS-PAF and AGEPC were inactivated by a 5-min incubation with ALF, the acid-labile factor in normal human serum that rapidly destroys AGEPC. 4. HS-PAF was demonstrated to be functionally similar to AGEPC by cross-desensitization experiments. In the absence of Ca++, HS-PAF and AGEPC cross-desensitized washed rabbit platelets to subsequent stimulation by either HS-PAF or AGEPC after recalcification. 5. HS-PAF was demonstrated to be structurally similar to AGEPC by several simple chemical tests for functional groups.